The present invention generally relates to a primary battery, and more particularly, to a divalent silver oxide for use in an alkaline cell and a method of manufacturing the same.
With the recent progress in the field of electronics, various electronic instruments, such as electronic calculators, electronic wrist watches and the like have been miniaturized in size, while compact and small-sized batteries of monovalent silver oxide (Ag.sub.2 O)-zinc(Zn) group have been commercialized and put into practical use as an external source of electric power for driving such electronic instruments. Following the further miniaturization of the electronic instruments, however, development of batteries of still smaller size is strongly demanded for practical use, and thus attention is now focused on batteries which employ, as positive electrode active material, divalent silver oxide (AgO) having higher energy density per unit weight and volume than the monovalent silver oxide (Ag.sub.2 O).
The divalent silver oxide or AgO as described above has the energy density per unit weight 1.87 times larger, and energy density per volume 1.94 times larger than the monovalent silver oxide or Ag.sub.2 O. Accordingly, if Ag.sub.2 O is replaced by AgO to form an alkaline battery of AgO-Zn group, it becomes possible to increase the capacity by approximately 40% in the battery having the same dimensions and configuration. The divalent silver oxide presently available, however, is converted into a stable Ag.sub.2 O through discharging of oxygen gas upon contact with an alkaline electrolyte, thus presenting problems, for example, in that the voltage developed extends over two stages of potential, i.e., the potential of AgO and that of Ag.sub.2 O, while it is very dangerous, since leakage of liquid or explosion due to increase of internal pressure may be involved unless there is provided some means to absorb the oxygen gas thus generated in the interior of the battery. Meanwhile, even when the battery is provided with the oxygen gas absorbing function in the interior thereof, the high energy of AgO is not fully utilized through reduction of volume efficiency within the battery, thus it being impossible to achieve the desired end to highly increase the capacity of the battery.